The goal of the Instrumented Pipeline Initiative (IPI) is to address sensor system needs for low-cost monitoring and inspection as identified in the Department of Energy (DOE) National Gas Infrastructure Research & Development (R&D) Delivery Reliability Program Roadmap. This project intends to develop a new sensing and continuous monitoring system with alternative use as an inspection method.

There are over 250 thousand miles of transmission pipeline and over one million miles of aging distribution pipeline in use across the United States today (as illustrated in Figure 1). There is a need to develop economical approaches to monitor and inspect this vast network of pipeline systems for sabotage and failure. The objective of this initiative is to research technologies that monitor pipeline delivery integrity through a ubiquitous network of sensors and controllers to detect and diagnose incipient defects, leaks, and failures.

CTC will develop a network of sensors and perform laboratory testing to quantify the ability to monitor the integrity of our nation’s natural gas pipeline delivery system, which consists of a network of more than 1.4 million miles of aging transmission and distribution pipelines and bulk gas storage reservoirs. CTC will execute this instrumented pipeline initiative through a research, development, and testing program to develop prototype sensor/controller networks for the uninterrupted supervision of pipeline systems to detect, identify, and prevent (at an early stage) material defects, pipe faults, gas leakages, or major damage. Various types of pipe and construction materials will be analyzed during this R&D effort.

Nine specific tasks detail the activities that will be used to execute this project. CTC will assess the available technologies for pipeline integrity monitoring leading to defect detection and location. Following an initial technology assessment, CTC will investigate wave propagation as a plausible technology for the development and optimization of active sensing and as a means to classify and locate defects. Electrical power consumption of the sensor systems will be analyzed to support economic feasibility and sensor system and power selection. The selected technologies and system components will be implemented in a proof-of-concept demonstrator to validate operation and performance under typical pipeline conditions. A technology transition plan will be completed as part of the project final report. CTC will team with CMU on this effort.

Impact

This project seeks to provide a cost-effective and practical solution for securing the delivery and reliability of the Nation’s aging pipeline infrastructure. Instrumented pipeline technologies will allow industry to enhance pipeline security by improving the ability to detect and mitigate intrusion and assess vulnerabilies. A sensored pipeline will also permit early detection of leaks and failures thereby increasing the overall safety of the pipeline system.

Accomplishments (most recent listed first)

Program Management

Completed Midpoint Review

Presented a project demonstration at NETL Morgantown Facilities on November 13, 2009.

Prepared digital video of demonstration and hosted on website for NETL to download prior to physical demonstration meeting.

Prepared briefing slides for demonstration meeting.

Technology Status Assessment Summary

Delivered Technology Status Assessment (TSA)

Delivered revised TSA to include technology uncovered after original submission

Provided feedback on NETL-authored Project Summary

Wave Propagation Summary

Simulated Long distance propagation by reflecting waves off open pipe ends

A single node based sensor concept has been identified and the laboratory proof of concept system is based on this single node concept. In addition, a multiple node system has been identified for long distance testing. A preliminary power budget has been defined based on a 10V excitation of the PZT transducers. This budget is subject to change when a fully implementable system is defined.

Extraction of Reference-Free Features

Simulated and tested acoustic waves on pipes show complex modal and multipath propagation. The complexity of the waveform benefits the time reversal acoustic (TRA) approach to detecting defects.

Continued investigating the impact of environmental changes in a real world scenario on the time reversal detector.

Developed a robust, constant false alarm rate (CFAR) time reversal detector to minimize the effects of additive measurement noise.

Continued studying the impact of temperature and water loading on time reversal-based defect detection.

Two adaptive detectors were developed to detect damage in an environment with unknown and changing colored noise.

The first detector was designed around the important concept that, after performing a time reversal operation, the output signal closely resembles the original input signal. Changes in the pipe due to damage could be detected by comparing and matching the input and output signals. In this algorithm, the time reversal step was accomplished mathematically rather than physically. The data outside the frame of interest was used to estimate the noise. This detector only required one signal measurement to estimate the noise and detect defects. This detection scheme was used to develop the real-time detection system demonstrated at NETL in November.

The second adaptive detector was developed in a more mathematically rigorous fashion. The detector expands the formal time reversal detection scheme by determining the maximum likelihood estimate of the colored noise. Unlike the other adaptive detection scheme, the algorithm assumes the use of physical time reversal. Results with simulated data have shown the algorithm to be both robust and reliable with only two measurements (the forward signal and time reversed signal) needed. Due to the mathematical support of this detector, it should out-perform the other adaptive method. The next step is to test the algorithm with experimental data and integrate it with the experimental system.

Conducted PZFlex-based simulations to study the Lamb wave propagation in structures such as pipes and plates. Actuators and sensors are used to transmit adaptive excitation waveforms to probe the pipe. From the reflected and scatted elastic wave signals recorded at the sensors, the location and identity of the defect size and the characteristics is determined.

The first simulation scenario used two transducer arrays for receiving elastic waves that transmitted by an active source. This simulation set was created to simulate and understand sparse arrays used in detection of defects.

The second simulation scenario was created to study the wave scattering due to the presence of a defect. Gaussian probing signals were transmitted from the first transducer array using one transducer at a time and recorded at the receive transducer array.

In Summary, the TRA solution effectively focuses energy for use in determining changes to pipeline, including damage. This technique focuses the energy of all of the modes, paths, and dispersion at one point in time and space. This focused signal can then be used to characterize the pipe medium and the damage within it. Specifically time reversal focusing simplifies the response without a cost to signal strength, coherently focuses energy from dispersion, modes, and paths, and focusing occurs regardless of frequency or bandwidth.

Classification and Localization of Defects

Continued experimental testing of time domain windowing for defect localization.

Continued PZFlex simulations and animations using both single-antenna and multi (4)-antenna time reversal to evaluate mode conversion in the damage scenarios already studied. The modes generated in each case will be used to study compression (in both time and space) of the signals after time reversal.

Researched analytical models or Green’s functions for use with time reversal based localization algorithms in order to achieve accurate damage localization and high resolution imaging.

Developed a defect time reversal-based localization and imaging algorithm using sparsely spaced ultrasonic transducers.

In the PZFlex simulations, the transducer array is not a typical “phased array” because the inter-element spacing is larger than a wavelength. Thus, the individual transducer unit is considered to be sparsely deployed.

Proof of Concept Development and Implementation

Procured, setup and began utilizing initial lab proof-of-concept system

Collected the majority of data to date using the lab proof-of-concept system

Introduced and studied initial deployable concepts

Conducted numerous teleconferences with the gas pipeline industry and will continue to do so throughout the project

Technology Transition

Conducting industry consultation on a regular basis

Identifying market needs

Identifying technical challenges

CTC has evaluated acoustic propagation on pipes and has determined that the multimode and multipath propagation adds sensitivity to the TRA detection method. In addition, PZT transducers have been selected for use in the remainder of this project. Current and future efforts will determine the effectiveness of the TRA method for detection, classification, and localization of defects.

CTC has shown that Time Reversal focusing compensates for multiple modes and dispersion in the pipe environment, resulting in an enhanced signal-to-noise ratio and effective change detection by presenting a distinguishable peak. This technique has been effectively demonstrated in six laboratory circumstances, providing with comprehensive and promising results on guided wave focusing in a pipe with/without welded joint, with/without internal pressure, and detection of three different defects: lateral, longitudinal and corrosion-like.

Current Status

CTC has completed and submitted the final Technical Report the report has been reviewed and approved. The report is listed below under "Additional Information".

CTC has completed all deliverables associated with this project, thus the project has been completed.